No, I don't think this is a fungal infection, (for several reasons, other than the odd color patterns on the skin,) but unfortunately, Shawn Stewart's photos of it are in black and white--Which is weird. Why would anyone take a photo of a dart frog in black and white? The origin is listed as Brazil, and from what I've found so far, no one is offering them to the hobby yet, or working with them. I'll ask around and see if I get a response.
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Patty
Pahsimeroi, Idaho

D. auratus blue, auratus Ancon Hill, galactonotus orange, galactonotus yellow, fantasticus, reticulatus, imitator, castaneoticus, azureus, pumilio Bastimentos. P. lugubris, vittatus, terribilis mint green, terribilis orange.